This invention relates generally to a resonator assembly and mounting method wherein a crystal resonator is connected to a support along a linear strip where the resonator and support have one or more matched thermal characteristics. The invention more particularly relates, but is not limited, to a crystal resonator assembly and mounting method wherein a crystal resonator is mounted to a support along a segment of a line of an X-Y plane of the resonator which has a crystalline structure oriented relative to X-, Y- and Z-crystallographic axes. This particular example especially relates to a quartz crystal resonator which is to be connected to a Z-cut quartz crystal support because this resonator has the same thermal expansion coefficient and thermal expansion characteristics along such an X-Y segment as the Z-cut support, whereas these characteristics are substantially different from the Z-cut support in other directions of the resonator. Within a broader aspect of the invention, however, any chord extending across a surface of a resonator and spaced from the center of the active region of the resonator and any linear locus on the support to which the resonator is to be connected can be selected as the locations for their interconnection as long as either or both of the thermal expansion coefficient and the thermal expansion characteristics of the resonator and support along the chord and linear locus are matched.
Crystal resonators are used in sensing temperature and pressure and in providing a reference used in correcting for changes in the responses of the temperature and pressure sensors, which changes in the responses are caused by changes in temperature where the resonators are located. In at least one particular type of resonator used as a reference, the crystal which is to resonate is mounted to a crystalline support at a single point ("point" as used herein means a relatively small locus, such as a circular dot; its meaning includes but is not limited to, a geometric point of a geometric line). For example, a small dot of conductive glass frit has been used to mount a crystal resonator to a crystal support at a single point. A small dot of devitrifying glass frit has also been used adjacent the conductive glass frit to try to increase the overall strength of such single-point mount.
Although the aforementioned single-point mounted resonators are useful, the single-point mount is susceptible to being broken when the resonator is subjected to shock impulses, such as if the resonator is dropped or hit. To provide an improved mount, more than a single-point mount is needed; however, when a crystal is rigidly mounted at more than one point, it can be subjected to damaging stresses created when the crystal expands or contracts in response to temperature changes. That is, when a crystal is mounted only at one point, the remainder of the crystal is free to expand or contract. If the crystal were rigidly mounted at more than one point, on the other hand, the expansion or contraction would be resisted by the multiple mounting points at which the crystal is fixed. This could produce stresses which would in general affect the frequency-temperature response of the crystal and which could damage the crystal.
From the foregoing, there is the need for an improved mounting technique which more securely mounts a crystal resonator to its support, but which does not subject, or minimally subjects, the crystal resonator to influencing and/or damaging stresses in response to temperature changes.